Process for achieving custom mask to panel spacing in cathode ray tubes



R. KAUTZ Nov. 3, 1970 G.

- PROCESS FOR ACHIEVING CUSTOM MASK TO PANEL SPACING IN CATHODE RAY TUBES Filed Nov. 19, 1968 INVENTOR. GEORGE R. KAUTZ ATTORNEY United States Patent 3,537,161 PROCESS FOR ACHIEVING CUSTOM MASK TO PANEL SPACING IN CATHODE RAY TUBES George R. Kautz, Seneca Falls, N.Y., assignor to Sylvama Electric Products Inc., a corporation of Delaware Filed Nov. 19, 1968, Ser. No. 777,107 Int. Cl. H01 9/18, 9/36 US. Cl. 2925.15 Claims ABSTRACT OF THE DISCLOSURE Background of the invention The invention relates to cathode ray tubes and more particularly to a process for achieving accurate custom spacing between the aperture mask and a panel in a color cathode ray tube of the shadow mask type.

In a cathode ray tube employing an aperture shadow mask, the frame supporting the mask is usually oriented in a predeterminately spaced manner within the panel by bracket locating means on the mask frame mating with positioning means integral to the panel.

One of the problems encountered in the fabrication of screens for shadow mask tubes involves achieving accurate spacing between the aperture mask and the interior surface of the panel upon which the cathodoluminescent screen is disposed. Such spacing which is predetermined during the mask and panel assembly procedure facilitates subsequent photodeposition of the patterned screen on the panel. During the operation of the finished tube, the several electron beams emitted therein are influenced to cross one another at the mask apertures and impinge upon discretely related areas of the screen layer without overlapping one another. Usually the spacing between the mask and the screen is varied in a planned sequential manner progressing from the center portion of the mask toward the edge areas thereof to provide the proper spacing relationship between the mask apertures and discrete areas of the display screen.

In assembling the formed aperture portion of the mask to its strengthening frame to provide the mask-frame assembly, one of the conventional procedures comprises loeating the formed mask on a bed substantially contoured to the domed shape of the mask. With the mask so positioned, the frame is adjusted in a manner to achieve the desired dimensional relationship between the mask and the frame locating means, whereupon the mask is peripherally bonded to the adjusted frame. Many mask-frame combinations have been fabricated in this manner. Accordingly, with the aforementioned procedure a relative generalized spacing between the shaped mask and the panel is substantially achieved in the mask-panel assembly.

Another conventional procedure consists of welding the mask to the frame and then compromising the positioning and attachment of the frame locating means thereon to arrive at the desired dimensional relationship between the mask surface and the frame locating means.

Unfortunately, in the aforementioned conventional assembly procedures, the several tolerances inherent there- Patented Nov. 3, 1970 ice in, such as those encountered forming the aperture mask, attaching the mask to the frame, and manufacturing the panels, can only be considered in a generalized manner. However, it has been found that the normally accepted tolerances of the mask and panel may at times assume combined values in the subsequent assembly to effect resultant mask to panel spacings which have dimensional values other than those required to achieve the desired screen quality.

In turn, the undesired dimensional values of such mask to panel spacing affect the color purity of the dynamic display in the finished tube. Therefore, in order to attempt to achieve the desired mask to panel spacing, it has been a conventional procedure to utilize gauging means to match framed masks to panels. If the spacing between the mask and panel in the initial attempt at assembly does not meet the accepted tolerances, the mask is removed and positioned in a different panel and rechecked until a mask-panel combination is found that will fulfill the spacing specifications. An acceptable mask-panel combination is mated as an assembly and, as such, remains in associated relationship throughout subsequent processing into the completed tube. The aforedescribed matching procedure requires considerable time and handling which is detrimental to efiicient manufacturing. Furthermore, accurate and uniform mask to panel spacing is not fully achieved because of the additive tolerances inherent in the procedure.

Objects and summary of the invention It is an object of the invention to reduce the aforementioned difficulties and to provide a color cathode ray tube having an improved mask to panel spacing relation ship.

Another object is to provide a process for making a cathode ray tube mask-panel assembly having improved relationship between the aperture mask and the screen bearing portion of the panel.

A still further object is to provide a process for improving the mask to panel relationship during the manufacture of a mask-panel assembly.

The foregoing objects are achieved in one aspect of the invention by the provision of a process whereby the panel is positioned in a manner to receive a plurality of spacer sensing means which are placed to contact discrete areas of the interior contour of the panel. The mask supporting frame with the mask portion fitted thereon is positioned relative to the mask positioning means in the panel in a manner for the masking portion to make contact with the several spacer sensing means located on the panel. The frame of the mask is then oriented relative to positioning means therefor integral to the panel. Pressure is applied against the interior surface of the mask portion by pressure means in discrete areas to seat the mask portion against the spacer sensing means, thereby modifying the mask contour to make it compatible with that of the panel. The oriented mask portion is then attached to its supporting frame at a plurality of separated perimetric areas to provide a framed mask assembly whereof the discretely formed mask portion is custommodified to achieve determinate spacing relative to the interior contour of the panel.

Brief description of the drawings FIG. 1 is a general plan view of a conventional shadow mask type of cathode ray tube comprising a mask positioned in spaced relationship to a screen bearing panel;

FIG. 2 is a plan view of a typical mask-panel assembly, before incorporation into the tube structure shown in FIG. 1, taken along the line 2-2 of FIG. 3 illustrating a significant step in the mask-panel manufacturing process;

3 FIG. 3 is a sectional view showing the mask-panel manufacturing process as shown in FIG. 2 taken along the line 33 thereof; and

FIG. 4 is asectional view of a mask and a positionally related panel illustrating another process embodiment of the invention.

Description of the preferred embodiment For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following specification and appended claims in connection with the aforedescribed drawings.

With reference to the drawings, FIG. 1 illustrates a conventional shadow mask type of color cathode ray tube 11. Oriented within the neck portion 13 of the tube envelope 15 is an electron gun structure 17. This generalized structure comprises three electron beam emitters wherefrom beams 19 are directed to converge at the aperture mask 21, which is a thin metallic foraminous member. After convergence, the beams pass the mask apertures 23 to impinge upon a patterned cathodoluminescent screen 25 therebeneath which is suitably disposed upon the interior surface,27 of the panel portion 29 of the tube. The formed aperture mask 21.is suitably attached to a strengthening frame 31 which, in turn, has bracket locating means 33 thereon to mate with positioning means 35 integral to the panel to form the mask-panel assembly 37. The spacing between the formed mask 21 and the interior surface 27 of the panel is conventionally referred to as Q spacing. Such spacing is of predetermined values, being achieved by resolving the proper distance d between the frame locating means 33 and the interior surface of the panel immediately prior to the attachment of the formed aperture mask 21 to its supporting frame 31. As shown, the mask-panel assembly 37 is suitably joined to the funnel portion 39 of the tube envelope along the seal line 41.

With particular reference to FIGS. 2 and 3 there is illustrated the process whereby the predetermined mask to panel spacing is discretely elfected during the manufacture of the mask-panel assembly. The glass face panel 29 is positioned on suitably panel supporting means 43 in a manner to permit a plurality of spacer sensing means 45 to be oriented to contact several discrete areas of the interior contour of the panel. These several spacers have specific dimensional heights that are consistent with the desired predetermined spacings between the formed mask and the contour of the panel at the particular locations whereat the respective sensers are positioned. As aforementioned, the desired mask to panel spacing is conventionally referenced as Q spacing. FIG. 2 shows a plan view of a substantially rectangular mask-panel assembly, looking into the panel from the seal line 41 during the assembly operation; wherein, for example, five of the aforementioned spacer sensing means 45 are utilized, one at substantially each of the four corner regions of the mask and one in substantially the center area thereof. It is not intended that the number of spacers be limited to five as any number in excess of four, one for each of the corner regions, could be utilized as desired.

In greater detail, each of the spacer sensing means 45, has a first contact surface 47 or sensing area that is of a form to substantially mate with the contour of a specific region of the interior surface of the panel 27. Substantially oppositely disposed on the spacer means, by at least a Q distance from the first contact or sensing area, is a second contact surface 49 formed as an anvil area having a contour substantially matching the predetermined general contour of the mask portion in the respective area.

To insure consistent placement of the several spacer means 45 on specific areas of the interior contour of the panel 29, spacer orientation means, such as a templet 51, is employed. Provisions in the templet are formed to accommodate the desired locationof each spacer. The

templet, per se, is constructed in a manner to facilitate free adjustment of each spacer to the related contour of the panel, while retaining the desired lateral orientation relationship of each spacer.

The mask supporting frame 31 with a mask aperture portion 21 fitted thereon, but not attached thereto, is positioned relative to the interior surface of the panel to enable the formedmask portion to make plural contact with the anvil areas 49 of the several spacer sensing means 45.

The mask frame is spacedly positioned within the panel by mating the frame locating means 33 with the appropriate positioning means 35 integral to the panel sidewall. This places the formed but unattached mask in a position to rest on the several anvil areas 49. Pressure means 52 providing areas of discrete pressure in the form of a plurality of individual pressure contactors 53, each having a seating surface 55, are positioned by pressure orientation means 57 in a manner that a respective seating surface 55 is applied against the interior surface of the mask 21 at discrete areas substantially opposite the anvil areas 49 of associated spacer means 45.

It has been found that the mask contour is advantageously adjusted when the anvil portion provides a seating surface 49 that at least equals the seating surface 55 a or pressure area of the related pressure contactor. Preferably, the anvil surface is of an area greater than that of the opposed seating surface to facilitate adequate seating of the mask when pressure is applied thereon. It is not intended that the aforementioned seating surface relationships be limiting as there may be instances where an anvil surface of an area smaller that that of the related pressure contactor may be advantageous. The individual pressure means 52 are separately movable with reference to the pressure orientation means 57, which is accommodated by means not shown. In this manner the pressure means provide a suflicient area of pressure to the individual pressure contactors to definitely seat the contacted mask portion against the corresponding sensing means. Thus, the shape of the mask contour is custom modified in accordance with the interior contour of the respective panel. While the mask is being held between the pressure contactors and the anvil areas of the spacer means, attachment is consummated between the mask portion and its supporting frame at a plurality of separated perimetric areas therearound. FIGS. 2 and 3 illustrate the mask panel assembly process at substantially this stage of fabrication. The attachment means 59 employs suitable bonding elements, as for example welding components, comprising a power source 61, control means 63, and two electrode members 65 and 67 respectively. Attachment welds 69 are consummated at spaced perimetric intervals around the region where the mask 21 overlaps the frame 31. Several of these attachment welds are shown in FIG. 3. In this manner, each mask contour is custom tailored and Q spaced according to the contour of the particular panel which will become part of the mated mask panel assembly.

Thus, the desired Q spacing is custom achieved for each assembly 37. After integrating the mask frame assembly, the pressure means are relieved from contact with the mask; whereupon, the framed mask is separated from the panel to permit removal of the spacer sensing means therefrom.

Another embodiment of the process is illustrated in FIG. 4, wherein spacer sensing means 45' having increased lengths are utilized to provide greater space for effecting the welding of the mask to the frame. Certain aspects in this embodiment are similar to elements already noted in describing the first embodiment. These common elements are referenced by like numerical designations. With the panel portion 29 positioned on the panel support means 43, the mask supported frame 31 is located distal thereto being predeterminately spaced from the mask frame positioning means 35 integral to the panel; the distance therebetween being designated as x. Since definite Q spacings between the mask and the panel are necessary, the length dimension of each spacer means 45 is designated as y and is equal to x plus Q. The frame 31 with the mask 21 fitted thereon, but not attached, is oriented by means not shown relative to the positioning means 35 in the panel with the mask portion 21 resting upon respective anvil surfaces 49 of the several spacer means 45'.

Spacer sensing means 45 has a first contact surface 47 or sensing area that is formed to substantially mate with the contour of a specific region of the interior surface of the panel 27. Substantially oppositely disposed on the spacer means, by at least a y distance from the first contact surface 47', is a second contact surface or anvil area 49'. This second contact surface has a contour substan tially matching the predetermined general contour of the mask portion in the respective area.

To achieve consistent placement of the several spacer means 45' on specific areas of the interior contour 27 of the panel 29, suitable spacer orientation means 51' is employed. This spacer orientation means, which is sup ported by means not shown, is formed to accommodate the desired location of each of the several spacers, and is constructed to facilitate free adjustment of each spacer means to the related contour of the panel surface, while maintaining the desired lateral orientation relationship of each spacer. This free adjustment facilitation is accomplished, for example, by providing free sliding accommodation of each spacer 45 in the orientation means 51'.

Pressure is applied to the mask portion by means already described wherein the individual pressure contactors 53 are activated whereupon the seating surface 55 of the respective contactors seats the mask on the corresponding anvil portions 49. With the mask so positioned and modified, it is then perimetrically attached to the frame 31 in the aforedescribed manner utilizing bonding means 59' comprising, for example, a power source 61, control means 63, and electrode members 65 and 67' respectively. After consummating the spaced apart perimetric welds 69, several of which are shown, the pressure means are relieved from contact with the mask portion, whereupon the framed mask is moved away from the panel to permit removal of the spacer sensing means 45'.

Thus, the two described embodiments of the process provide cathode ray tube mask panel assemblies wherein the predetermined spacings between the mask portion and the interior contour of the panel are custom achieved in a manner to provide Q spacings of improved accuracy and uniformity. The process also promotes increased manufacturing efficiency of a degree heretofore unattained. The speed of the fabrication operation is enhanced as each mask has contour portions thereof custom modified according to the contour characteristics of an initially related panel.

While substantially rectangular panels and masks are shown, it is not intended that the processes of the invention be limited thereo, as any shaped mask-panel assembly can be manufactured by the process embodiments described.

While there has been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

I claim:

1. A process for making a cathode ray tube mask-panel assembly wherein the aperture mask is supported on a frame oriented by positioning means within said panel, said process comprising the steps of:

positioning said panel on panel supporting means;

orienting a plurality of spacer sensing means to make contact with discrete areas of the interior contour of said panel to facilitate accurate spacing of said mask portion therefrom;

locating said supporting frame with said mask portion fitted thereon in a position relative to the interior surface of said panel to enable said mask portion to make plural contact with said spacer sensing means, said frame being oriented relative to the frame positioning means in said panel;

applying pressure means against the interior surface of said mask portion to provide pressure areas to seat said mask portion against said spacer sensing means and modify said mask contour making it compatible with that of said panel to provide a custom spacing relationship therebetween;

attaching said mask portion to said supporting frame at a plurality of separated perimetric areas therearound to provide a framed mask assembly wherein the mask portion thereof is determinately and spacedly related to the contour of said panel;

relieving said pressure means from contact with said mask portion; and

removing said spacer sensing means from contracting said panel and said mask.

2. A process for making a cathode ray tube maskpanel assembly according to claim 1 wherein said pressure means are applied against said mask portion at substantially the areas thereof supported by said spacer sensing means to effect a mask contour defined in spaced accordance therewith.

3. A process for making a cathode ray tube mask-panel assembly according to claim 1 wherein said mask supporting frame is located on positioning means in the form of studs integral to said panel during the steps wherein said seating pressure is applied to said mask portion and when said spaced mask portion is subsequently attached to said frame.

4. A process for making a cathode ray tube mask-panel assembly according to claim 1 wherein said mask supporting frame is located distal to and predeterminately spaced from said positioning means integral to said panel during the steps wherein said seating pressure is applied to said mask portion and when said spaced mask portion is sub sequently attached to said frame, said spacer sensing means being of lengths to effect the predetermined spacings between said mask portion and said panel in the subsequent assembly of said mask in said panel.

5. A process for making a substantially rectangular cathode ray tube mask-panel assembly according to claim 1 wherein said spacer sensing means are at least four in number being spaced relatively to the four corner areas of said panel.

References Cited UNITED STATES PATENTS 2,871,087 1/1959 Knochel 2925.l3 XR 3,335,479 8/1967 Morrell 29-2515 XR 3,351,996 11/1967 Fiore 29-25.15 XR 3,358,170 12/1967 Fiore 29--25.l5 XR 3,468,005 9/ 1969 Kautz 29-25.15

JOHN F. CAMPBELL, Primary Examiner R. B. LAZARUS, Assistant Examiner US. Cl. X.R. 2925 13 

